Re: Hidden ISP firewall/filtering

["Paul Melson" <pmelson () gmail com>]

> I recently purchased a Watchguard XTM2 to handle our firewall and VPN with
IPSec, but when 
> attempting to connect via VPN with IPSec, it gives a message of “VPN
gateway not responding 
> (waiting for MSG2)”  I have removed our watchguard from the network and
when I do a “shields 
> up” scan it shows all ports being closed.  Long story short . . . does
anyone know if there is > a way to find out if our ISP actually has a
firewall/filtering in place, or b) have any other > thoughts.

You should be able to portscan with a tool like NMap or similar from a
switch connected to the external interface of the firewall and then scan
from another vantage point that traverses the ISP (home, coffee shop,
airport, etc.)  If the ports appear open on the attached switch and closed
from another location, then you know there's filtering going on.
Determining exactly where along the path can be difficult, but trying from
multiple vantage points should yield some different results if it's not your
ISP.

PaulM



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